U.S. Pat. No. 5,680,109 A describes a differential-pressure sensor which has a high-pressure impulse line and a low-pressure impulse line, which are respectively connected to a process connection. An absolute-pressure sensor is respectively connected to the high-pressure impulse line and the low-pressure impulse line. In order to determine whether the high-pressure impulse line or the low-pressure impulse line is blocked, a noise signal from the corresponding absolute-pressure sensor is determined. A variance in the noise signal is determined and compared to a threshold value. If the variance is less than the threshold value, an impulse line blockage is indicated.
The approach above of analyzing fluctuations is, in principle, expedient, but very complex, since additional sensors are required.